In a paper recently published in the Philosophical Transactions of the Royal Society of London, the writer describes the discovery of certain small Tylenchoid nematodes in the swollen stems of the seedling oats suffering from frit-fly attack at Winches Farm, St. Albans. Adults of both sexes and larvæ undergoing the last two moults were found in the destroyed plant tissues surrounding the fly larvæ. The spermatized female worms were next discovered within the body-cavity of the frit-fly larvæ. In due course, they were obtained from pupæ of the fly, having increased in size, and finally were found within adult flies of both sexes lying coiled within the abdomen as comparatively large sausage-shaped worms. As a result of the presence of the worm, the flies are sterilised, being unable to develop their reproductive organs. The worms become viviparous and shed large numbers of larvæ into the body-cavity of the fly and these, after undergoing a certain amount of growth, make their way into the gut of the host and pass to the exterior via the anus. In the present communication a brief account is given of the principal observations on the new parasite, its life-history and the effects on the host, described in detail in the original paper.

This survey is a continuation of that carried out by Morgan (1924–25). The area covered, however, is more extensive, and the investigation extends over a period of four years (October, 1924 to October, 1928).

The early accounts of the morphology and life-cycle of Heterodera schachtii, were, like much of the subsequent work on this subject, the result of observations carried out on the strain of H. schachtii parasitic on sugar-beet in Germany.

A biological study of the fauna of sewage-treatment plants was pursued by the writer for two years, from June 1927, thanks to the generosity of the Grocers' Company. The programme laid down included a qualitative and quantitative survey of the fauna and a collection of data on such physico-chemical factors as hydrogen ion concentration and oxygen requirement, with a view to seeking correlations between the two groups of phenomena.

Owing to the comparatively little use made of the flesh of the goat in this country, the helminthic parasites of this host have been far less studied than those found in other domestic animals. In other countries, where the goat plays a far greater economic rôle, a large number of parasitic worms have been recorded.

A preliminary publication recording the discovery of mustard as a factor influencing the cyst formation of Heterodera schachtii, and describing various experiments to demonstrate the effects of this factor, has already been made. Mustard seedlings grown to a height of about three inches and then broken down in soil in which a potato plant was immediately thereafter grown, were found to exert some influence on the development of the nematode, which partially inhibited the formation of cysts on the roots of the potato plant. The reduction in the number of cysts developed on the roots of a plant so treated, as compared with a plant grown in infected soil without mustard, was found to average over 60 per cent.

Galls, in the inflorescences of various species of grasses, caused by nematodes have been known since Steinbuch first described them, in 1799, in the flowers of Agrostis capillaris and Phalaris phleoides. Since that time they have been found in several other species of grasses and have been studied principally by entomologists interested in galls caused by insects. The causative organisms have received but little serious attention from helminthologists in recent years.

The genus Subulura was established in 1860 by Molin for a nematode from Scops brasiliannus and at the present day includes some forty species, mostly in birds. Five species have been reported from primates. Three of these are little known and are still only provisionally retained within this genus. These are S. sarasinorum (from Loris), S. otolicni (from Galago) and S. perarmata (from Tarsius). They are discussed below. The remaining species S. distans (from Cercopithecidæ) and S. jacchi (from Cebidæ and Hapalidæ) are of sufficient importance to merit fuller consideration. The first-mentioned is only incompletely known although the second has been recently re-described by Barreto (1919). During an expedition in 1928 to the Lesser Antilles, I was able to collect a large number of specimens of Subulura from the African Monkeys in St. Kitts. These, together with specimens of S. distans and S. jacchi in the collections of the Department of Helminthology of the London School of Hygiene and Tropical Medicine, provided the material on which this paper is based.

This is the third and final paper of a series which constitutes a report on a biological investigation of sewage, undertaken by the writer as a Research Scholar of the Grocers' Company. Of the previous two papers, the first (1929) describes a colorimeter and the second (1930) is a general report on the work as a whole. Since the nematodes form a neglected and not inconsiderable section of the fauna of most sewage plants, special attention was accorded them, and an account of them is given separately here instead of rendering the general report unbalanced and unwieldy by being included there.

(1) During the routine examination of the fauna of samples of clinker removed from the filter beds of Brent Sewage Farm several species of Rhabdilis were met with, one at least of which cannot be relegated to any species as yet described. A new species is therefore suggested for its reception and the name succaris has been given to suggest its origin from the sewage farm.

(2) An account is given of its structure. While being typical for the genus, the lips and bursal rays do not agree with any known species.

(3) Two distinct strains were reared by means of different culture media, differing quite definitely in length. A thousand worms were measured and these differences were found to remain very constant. The relative measurements have not been materially altered.

(4) The length of the large worms has been diminished by means of a return to the original food.

(5) The cultivated strain shows greater variability than the original strain.

(6) Two graphs and a table summarising the results are shown.

During 1928 I was able, as Milner Research Fellow in the Department of Helminthology of the London School of Hygiene and Tropical Medicine, to make an extended survey of the parasites of man and the domestic animals in the British West Indies. A report on the former has already been published (1929). In examining the parasites of domestic animals, I was given every facility by the local authorities, and I am especially indebted to Captain H. V. Metivier, B.Sc., M.R.C.V.S., of Trinidad, whose assistance and knowledge of the local parasitic problems was invaluable.

In the majority of cases it is almost impossible to identify the species of helminths in our domestic stock by an examination of the eggs found in their droppings. In the case of sheep and goats, this is particularly so since these hosts harbour several worms with eggs which are, apparently, identical in shape, size and stage of development.

The following collection of Cestodes has been brought together by Prof. A. S. Pearse, of the Duke University, Durham, N.C., during a sojourn in Nigeria for the purpose of studying the parasites of rodents and insectivores.

In November, 1926, the writer observed the active revival of larvæ of Tylenchus dipsaci in water after being kept in a dry condition since September, 1920; a period of just over 6 years. These almost adult larvæ, which had been collected from Narcissus bulbs, were richly supplied with an abundance of reserve food bodies in the wall of the intestine and an attempt was made to determine the nature of these reserves. Various tests were carried out with different chemical reagents and stains and it was finally found that they were composed of fats in the form of small, spherical droplets of oil of variable size. Following these observations, as opportunity arose, other plant-parasitic and free-living nematodes have been examined for the presence of fats in and around the intestinal wall.

The lungworm genus Crenosoma, founded by Molin in 1861, was redescribed in 1928 by Skrjabin and Petrow. To the two existing species, C. striatum (Zeder, 1800) from the hedgehog (Erinaceus europæus L.) and C. vulpis (Dujardin, 1845) from the fox (Vulpes vulpes L.), these writers added a third species, C. taiga, from the lungs of Kolonocus sibiricus (Pall.) in Russia. A generic diagnosis based on a study of these three species was supplied, and the wolf (Canis lupus L.) was recorded as a new host for Crenosoma vulpis.

The writer established the genus Cylindrogaster in 1927 for the reception of a nematode found in cultures of rat's fæces. Its principal distinguishing features were the possession of very long buccal rods and an elongate, cylindrical, muscular first œsophageal bulb. The male possessed 10 caudal papillæ arranged in three groups disposed in a manner exactly similar to that of the caudal papilæ in many species of Diplogaster, Odontopharynx longicaudata and Tylopharynx striata.